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116-524: The Apple A6 is said to use a 1.3 GHz custom Apple-designed ARMv7-A architecture based dual-core CPU , called Swift , rather than a licensed CPU from ARM like in previous designs, and an integrated 266 MHz triple-core PowerVR SGX543MP3 graphics processing unit (GPU). The Swift core in the A6 uses a new tweaked instruction set featuring some elements of the ARM Cortex-A15 such as support for

232-467: A 74158 . The next major difference was to simplify the registers. To start with, one of the two accumulators was removed. General-purpose registers like accumulators have to be accessed by many parts of the instruction decoder, and thus require significant amounts of wiring to move data to and from their storage. Two accumulators makes many coding tasks easier, but costs the chip design itself significant complexity. Further savings were made by reducing

348-557: A CMOS version, the 65C02 . This continues to be widely used in embedded systems , with estimated production volumes in the hundreds of millions. The 6502 was designed by many of the same engineers that had designed the Motorola 6800 microprocessor family. Motorola started the 6800 microprocessor project in 1971 with Tom Bennett as the main architect. Motorola's engineers could run analog and digital simulations on an IBM 370-165 mainframe computer. The chip layout began in late 1972,

464-538: A conscious attempt of eight former Motorola employees who worked on the development of the 6800 system to put out a part that would replace and outperform the 6800, yet undersell it. With the benefit of hindsight gained on the 6800 project, the MOS Technology team headed by Chuck Peddle, made the following architectural changes in the Motorola CPU… The main change in terms of chip size was the elimination of

580-470: A contemporaneous competitor, the Intel 8080 , which likewise has one 8-bit accumulator and a 16-bit program counter, but has six more general-purpose 8-bit registers (which can be combined into three 16-bit pointers) and a larger 16-bit stack pointer. In order to make up somewhat for the lack of registers, the 6502 includes a zero page addressing mode that uses one address byte in the instruction instead of

696-861: A customer reaches foundry tapeout or prototyping. 75% of ARM's most recent IP over the last two years are included in ARM Flexible Access. As of October 2019: Arm provides a list of vendors who implement ARM cores in their design (application specific standard products (ASSP), microprocessor and microcontrollers). ARM cores are used in a number of products, particularly PDAs and smartphones . Some computing examples are Microsoft 's first generation Surface , Surface 2 and Pocket PC devices (following 2002 ), Apple 's iPads , and Asus 's Eee Pad Transformer tablet computers , and several Chromebook laptops. Others include Apple's iPhone smartphones and iPod portable media players , Canon PowerShot digital cameras , Nintendo Switch hybrid,

812-820: A design service foundry offers lower overall pricing (through subsidisation of the licence fee). For high volume mass-produced parts, the long term cost reduction achievable through lower wafer pricing reduces the impact of ARM's NRE ( non-recurring engineering ) costs, making the dedicated foundry a better choice. Companies that have developed chips with cores designed by Arm include Amazon.com 's Annapurna Labs subsidiary, Analog Devices , Apple , AppliedMicro (now: MACOM Technology Solutions ), Atmel , Broadcom , Cavium , Cypress Semiconductor , Freescale Semiconductor (now NXP Semiconductors ), Huawei , Intel , Maxim Integrated , Nvidia , NXP , Qualcomm , Renesas , Samsung Electronics , ST Microelectronics , Texas Instruments , and Xilinx . In February 2016, ARM announced

928-462: A flaw was very high. In most cases, 90% of such designs were flawed, resulting in a 10% yield. The price of the working examples had to cover the production cost of the 90% that were thrown away. In 1973, Perkin-Elmer introduced the Micralign system, which projected an image of the mask on the wafer instead of requiring direct contact. Masks no longer picked up dirt from the wafers and lasted on

1044-399: A greater extent than in many other designs; the two-phase clock (supplying two synchronizations per cycle) could thereby control the machine cycle directly. This design also led to one useful design note of the 6502, and the 6800 before it. Because the chip only accessed memory during a certain part of the clock cycle, and this duration was indicated by the φ2-low clock-out pin, other chips in

1160-807: A lawsuit settlement, and Intel took the opportunity to supplement their i960 line with the StrongARM. Intel later developed its own high performance implementation named XScale , which it has since sold to Marvell . Transistor count of the ARM core remained essentially the same throughout these changes; ARM2 had 30,000 transistors, while ARM6 grew only to 35,000. In 2005, about 98% of all mobile phones sold used at least one ARM processor. In 2010, producers of chips based on ARM architectures reported shipments of 6.1 billion ARM-based processors , representing 95% of smartphones , 35% of digital televisions and set-top boxes , and 10% of mobile computers . In 2011,

1276-504: A merchant foundry that holds an ARM licence, such as Samsung or Fujitsu, can offer fab customers reduced licensing costs. In exchange for acquiring the ARM core through the foundry's in-house design services, the customer can reduce or eliminate payment of ARM's upfront licence fee. Compared to dedicated semiconductor foundries (such as TSMC and UMC ) without in-house design services, Fujitsu/Samsung charge two- to three-times more per manufactured wafer . For low to mid volume applications,

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1392-450: A party, was a way to share some of the internal wiring to allow the ALU to be reduced in size. Despite their best efforts, the final design ended up being 5 mils too wide. The first 6502 chips were 168 by 183 mils (4.3 mm × 4.6 mm), for an area of 19.8 mm . The original version of the processor had no rotate right (ROR) capability, so the instruction was omitted from

1508-504: A portfolio of semiconductor patents. Allen-Bradley decided not to fight this case and sold their interest in MOS Technology back to the founders. Four of the former Motorola engineers were named in the suit: Chuck Peddle, Will Mathys, Bill Mensch and Rod Orgill. All were named inventors in the 6800 patent applications. During the discovery process, Motorola found that one engineer, Mike Janes, had ignored Peddle's instructions and brought his 6800 design documents to MOS Technology. In March 1976,

1624-558: A quirk of the 6502's design, the CPU left the memory untouched for half of the time. Thus by running the CPU at 1 MHz, the video system could read data during those down times, taking up the total 2 MHz bandwidth of the RAM. In the BBC Micro, the use of 4 MHz RAM allowed the same technique to be used, but running at twice the speed. This allowed it to outperform any similar machine on

1740-455: A ready-to-manufacture verified semiconductor intellectual property core . For these customers, Arm Holdings delivers a gate netlist description of the chosen ARM core, along with an abstracted simulation model and test programs to aid design integration and verification. More ambitious customers, including integrated device manufacturers (IDM) and foundry operators, choose to acquire the processor IP in synthesizable RTL ( Verilog ) form. With

1856-476: A set of chips that could sell at $ 20 to compete with the recently introduced Intel 4040 that sold for $ 29 in a similar complete chipset. Chips are produced by printing multiple copies of the chip design on the surface of a wafer , a thin disk of highly pure silicon. Smaller chips can be printed in greater numbers on the same wafer, decreasing their relative price. Additionally, wafers always include some number of tiny physical defects that are scattered across

1972-517: A signed 8-bit offset relative to the instruction after the branch; the numerical range −128..127 therefore translates to 128 bytes backward and 127 bytes forward from the instruction following the branch (which is 126 bytes backward and 129 bytes forward from the start of the branch instruction). Accumulator mode operates on the accumulator register and does not need any operand data. Immediate mode uses an 8-bit literal operand. The indirect modes are useful for array processing and other looping. With

2088-686: A simple chip design could nevertheless have extremely high performance, much higher than the latest 32-bit designs on the market. The second was a visit by Steve Furber and Sophie Wilson to the Western Design Center , a company run by Bill Mensch and his sister, which had become the logical successor to the MOS team and was offering new versions like the WDC 65C02 . The Acorn team saw high school students producing chip layouts on Apple II machines, which suggested that anyone could do it. In contrast,

2204-551: A small team to design the actual processor based on Wilson's ISA. The official Acorn RISC Machine project started in October 1983. Acorn chose VLSI Technology as the "silicon partner", as they were a source of ROMs and custom chips for Acorn. Acorn provided the design and VLSI provided the layout and production. The first samples of ARM silicon worked properly when first received and tested on 26 April 1985. Known as ARM1, these versions ran at 6 MHz. The first ARM application

2320-434: A special case; not only are they allowed to sell finished silicon containing ARM cores, they generally hold the right to re-manufacture ARM cores for other customers. Arm Holdings prices its IP based on perceived value. Lower performing ARM cores typically have lower licence costs than higher performing cores. In implementation terms, a synthesisable core costs more than a hard macro (blackbox) core. Complicating price matters,

2436-521: A supplier of electronic components and industrial controls, acquired a majority interest in 1970. The company designed and fabricated custom ICs for customers and had developed a line of calculator chips. After the Mostek efforts fell through, Peddle approached Paivinen, who "immediately got it". On 19 August 1974, Chuck Peddle, Bill Mensch, Rod Orgill, Harry Bawcom, Ray Hirt, Terry Holdt, and Wil Mathys left Motorola to join MOS. Mike Janes joined later. Of

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2552-428: A system could access memory during those times when the 6502 was off the bus. This was sometimes known as "hidden access". This technique was widely used by computer systems; they would use memory capable of access at 2 MHz, and then run the CPU at 1 MHz. This guaranteed that the CPU and video hardware could interleave their accesses, with a total performance matching that of the memory device. Because this access

2668-825: A variety of licensing terms, varying in cost and deliverables. Arm Holdings provides to all licensees an integratable hardware description of the ARM core as well as complete software development toolset ( compiler , debugger , software development kit ), and the right to sell manufactured silicon containing the ARM CPU. SoC packages integrating ARM's core designs include Nvidia Tegra's first three generations, CSR plc's Quatro family, ST-Ericsson's Nova and NovaThor, Silicon Labs's Precision32 MCU, Texas Instruments's OMAP products, Samsung's Hummingbird and Exynos products, Apple's A4 , A5 , and A5X , and NXP 's i.MX . Fabless licensees, who wish to integrate an ARM core into their own chip design, are usually only interested in acquiring

2784-477: A visit to another design firm working on modern 32-bit CPU revealed a team with over a dozen members who were already on revision H of their design and yet it still contained bugs. This cemented their late 1983 decision to begin their own CPU design, the Acorn RISC Machine. The original Berkeley RISC designs were in some sense teaching systems, not designed specifically for outright performance. To

2900-499: Is hardwired to memory page $ 01 , i.e. the address range $ 0100 – $ 01FF ( 256 – 511 ). Software access to the stack is done via four implied addressing mode instructions, whose functions are to push or pop (pull) the accumulator or the processor status register. The same stack is also used for subroutine calls via the JSR (jump to subroutine) and RTS (return from subroutine) instructions and for interrupt handling. The chip uses

3016-536: Is a little-endian 8-bit processor with a 16-bit address bus . The original versions were fabricated using an 8 µm process technology chip with a die size of 3.9 mm × 4.3 mm (153 by 168 mils), for a total area of 16.6 mm . The internal logic runs at the same speed as the external clock rate. It featured a simple pipeline; on each cycle, the processor fetches one byte from memory and processes another. This means that any single instruction can take as few as two cycles to complete, depending on

3132-479: Is called Apple A6X and is found only in the fourth generation iPad . ARM architecture ARM (stylised in lowercase as arm , formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine ) is a family of RISC instruction set architectures (ISAs) for computer processors . Arm Holdings develops the ISAs and licenses them to other companies, who build the physical devices that use

3248-468: Is capable of performing addition and subtraction in binary or binary-coded decimal . Placing the CPU into BCD mode with the SED (set D flag) instruction results in decimal arithmetic, in which $ 99 + $ 01 would result in $ 00 and the carry (C) flag being set. In binary mode ( CLD , clear D flag), the same operation would result in $ 9A and the carry flag being cleared. Other than Atari BASIC , BCD mode

3364-749: The Advanced SIMD v2 , and VFPv4. Analysis suggests that the Swift core has a triple-wide frontend and two FPUs , compared with a two-wide core with a single FPU in the Cortex-A9 based predecessor. The A6 processor package also incorporates 1 GB of LPDDR2-1066 RAM compared with 512MB of LPDDR2-800 RAM in the Apple A5 providing double the memory capacity while increasing the theoretical memory bandwidth from 6.4 GB/s to 8.5 GB/s. The A6 includes an upgraded image signal processor (ISP), that compared with

3480-611: The Commodore PET and Apple II , both released in 1977. It was later used in the Atari 8-bit computers , Acorn Atom , BBC Micro , VIC-20 and other designs both for home computers and business, such as Ohio Scientific and Oric computers . The 6510 , a direct successor of the 6502 with a digital I/O port and a tri-state address bus, was the CPU utilized in the best-selling Commodore 64 home computer. Another important use of

3596-603: The PC ). The ARM2 had a transistor count of just 30,000, compared to Motorola's six-year-older 68000 model with around 68,000. Much of this simplicity came from the lack of microcode , which represents about one-quarter to one-third of the 68000's transistors, and the lack of (like most CPUs of the day) a cache . This simplicity enabled the ARM2 to have a low power consumption and simpler thermal packaging by having fewer powered transistors. Nevertheless, ARM2 offered better performance than

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3712-689: The Wii security processor and 3DS handheld game consoles , and TomTom turn-by-turn navigation systems . In 2005, Arm took part in the development of Manchester University 's computer SpiNNaker , which used ARM cores to simulate the human brain . ARM chips are also used in Raspberry Pi , BeagleBoard , BeagleBone , PandaBoard , and other single-board computers , because they are very small, inexpensive, and consume very little power. The 32-bit ARM architecture ( ARM32 ), such as ARMv7-A (implementing AArch32; see section on Armv8-A for more on it),

3828-406: The operating system uses most of zero page, leaving only a handful of locations for the user. Addressing modes also include implied (1-byte instructions); absolute (3 bytes); indexed absolute (3 bytes); indexed zero-page (2 bytes); relative (2 bytes); accumulator (1); indirect,x and indirect,y (2); and immediate (2). Absolute mode is a general-purpose mode. Branch instructions use

3944-445: The stack register from 16 to 8 bits, meaning that the stack could only be 256 bytes long, which was enough for its intended role as a microcontroller. The 16-bit IX index register was split in two, becoming X and Y. More importantly, the style of access changed. In the 6800, IX held a 16-bit address which was offset by an 8-bit number stored with the instruction, and added together. In the 6502 (and most other contemporary designs),

4060-615: The tri-state drivers from the address bus outputs. A three-state bus has states for 1 , 0 and high impedance . The last state is used to allow other devices to access the bus, and is typically used for multiprocessing , or more commonly in these roles, for direct memory access (DMA). While useful, this feature is expensive in terms of on-chip circuitry. The 6502 simply removed this feature, in keeping with its design as an inexpensive controller being used for specific tasks and communicating with simple devices. Peddle suggested that anyone who required this style of access could implement it with

4176-436: The "EXORciser" debugging system, onsite training and field application engineer support. Both Intel and Motorola had initially announced a US$ 360 price for a single microprocessor. The actual price for production quantities was much less. Motorola offered a design kit containing the 6800 with six support chips for US$ 300 . Peddle, who would accompany the salespeople on customer visits, found that customers were put off by

4292-441: The "layout" was a very manual process done with color pencils and vellum paper . The layout consisted of thousands of polygon shapes on six different drawings; one for each layer of the fabrication process. Given the size limits, the entire chip design had to be constantly considered. Mensch and Paivinen worked on the instruction decoder while Mensch, Peddle and Orgill worked on the ALU and registers. A further advance, developed at

4408-571: The 16-bit base address was stored in the instruction, and the 8-bit X or Y was added to it. Finally, the instruction set was simplified, freeing up room in the decoder and control logic. Of the original 72 instructions in the 6800, 56 were implemented. Among those removed were instructions that operated between the 6800's two accumulators, and several branch instructions inspired by the PDP-11 . The chip's high-level design had to be turned into drawings of transistors and interconnects. At MOS Technology,

4524-468: The 32-bit ARM architecture was the most widely used architecture in mobile devices and the most popular 32-bit one in embedded systems. In 2013, 10 billion were produced and "ARM-based chips are found in nearly 60 percent of the world's mobile devices". Arm Holdings's primary business is selling IP cores , which licensees use to create microcontrollers (MCUs), CPUs , and systems-on-chips based on those cores. The original design manufacturer combines

4640-416: The 5/6 cycle "(indirect),y" mode, the 8-bit Y register is added to a 16-bit base address read from zero page, which is located by a single byte following the opcode. The Y register is therefore an index register in the sense that it is used to hold an actual index (as opposed to the X register in the 6800, where a base address was directly stored and to which an immediate offset could be added). Incrementing

4756-558: The 6500 family was in video games. The first to make use of the processor design was the 1977 Atari VCS, later renamed the Atari 2600 . The VCS used a 6502 variant named the 6507 , which had fewer pins, so it could address only 8  KB of memory. Millions of the Atari consoles would be sold, each with a MOS processor. Another significant use was by the Nintendo Entertainment System and Famicom. The 6502 used in

Apple A6 - Misplaced Pages Continue

4872-418: The 6501 appeared in several publications the first week of August 1975. The 6501 would be for sale at Wescon for $ 20 each. In September 1975, the advertisements included both the 6501 and the 6502 microprocessors. The 6502 would cost only $ 25 (equivalent to $ 142 in 2023). When MOS Technology arrived at Wescon, they found that exhibitors were not permitted to sell anything on the show floor. They rented

4988-411: The 6502 or variations of the basic design. Soon after the 6502's introduction, MOS Technology was purchased outright by Commodore International , who continued to sell the microprocessor and licenses to other manufacturers. In the early days of the 6502, it was second-sourced by Rockwell and Synertek , and later licensed to other companies. In 1981, the Western Design Center started development of

5104-445: The 6800's headlining features was an onboard voltage doubler that allowed a single +5 V supply be used for +5, −5 and +12 V internally, as opposed to other chips of the era like the Intel 8080 that required three separate supply pins. While this feature reduced the complexity of the power supply and pin layout, it still required separate power line to the various gates on the chip, driving up complexity and size. By moving to

5220-416: The 6800. They would not run 6800 software because they had a different instruction set, different registers, and mostly different addressing modes. Rod Orgill was responsible for the 6501 design; he had assisted John Buchanan at Motorola on the 6800. Bill Mensch did the 6502; he was the designer of the 6820 Peripheral Interface Adapter (PIA) at Motorola. Harry Bawcom, Mike Janes and Sydney-Anne Holt helped with

5336-764: The ARM core with other parts to produce a complete device, typically one that can be built in existing semiconductor fabrication plants (fabs) at low cost and still deliver substantial performance. The most successful implementation has been the ARM7TDMI with hundreds of millions sold. Atmel has been a precursor design center in the ARM7TDMI-based embedded system. The ARM architectures used in smartphones, PDAs and other mobile devices range from ARMv5 to ARMv8-A . In 2009, some manufacturers introduced netbooks based on ARM architecture CPUs, in direct competition with netbooks based on Intel Atom . Arm Holdings offers

5452-584: The ARM instruction sets. These cores must comply fully with the ARM architecture. Companies that have designed cores that implement an ARM architecture include Apple, AppliedMicro (now: Ampere Computing ), Broadcom, Cavium (now: Marvell), Digital Equipment Corporation , Intel, Nvidia, Qualcomm, Samsung Electronics, Fujitsu , and NUVIA Inc. (acquired by Qualcomm in 2021). On 16 July 2019, ARM announced ARM Flexible Access. ARM Flexible Access provides unlimited access to included ARM intellectual property (IP) for development. Per product licence fees are required once

5568-696: The ARM6, first released in early 1992. Apple used the ARM6-based ARM610 as the basis for their Apple Newton PDA. In 1994, Acorn used the ARM610 as the main central processing unit (CPU) in their RiscPC computers. DEC licensed the ARMv4 architecture and produced the StrongARM . At 233  MHz , this CPU drew only one watt (newer versions draw far less). This work was later passed to Intel as part of

5684-582: The Built on ARM Cortex Technology licence, often shortened to Built on Cortex (BoC) licence. This licence allows companies to partner with ARM and make modifications to ARM Cortex designs. These design modifications will not be shared with other companies. These semi-custom core designs also have brand freedom, for example Kryo 280 . Companies that are current licensees of Built on ARM Cortex Technology include Qualcomm . Companies can also obtain an ARM architectural licence for designing their own CPU cores using

5800-419: The CPU can be in only one mode, but it can switch modes due to external events (interrupts) or programmatically. The original (and subsequent) ARM implementation was hardwired without microcode , like the much simpler 8-bit 6502 processor used in prior Acorn microcomputers. The 32-bit ARM architecture (and the 64-bit architecture for the most part) includes the following RISC features: To compensate for

5916-401: The CPU designs available. Their conclusion about the existing 16-bit designs was that they were a lot more expensive and were still "a bit crap", offering only slightly higher performance than their BBC Micro design. They also almost always demanded a large number of support chips to operate even at that level, which drove up the cost of the computer as a whole. These systems would simply not hit

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6032-490: The DRAM chip. Berkeley's design did not consider page mode and treated all memory equally. The ARM design added special vector-like memory access instructions, the "S-cycles", that could be used to fill or save multiple registers in a single page using page mode. This doubled memory performance when they could be used, and was especially important for graphics performance. The Berkeley RISC designs used register windows to reduce

6148-500: The ISP in the A5, improves the speed of image capture, low-light performance, noise reduction, and video stabilization. The A6 is manufactured by Samsung on a high-κ metal gate (HKMG) 32 nm process and the chip is 96.71 mm large, which is 22% smaller than the A5. The A6 also consumes less energy than its predecessor. A version of the A6 with higher frequency and four graphic cores

6264-559: The MacArthur Suite at the St. Francis Hotel and directed customers there to purchase the processors. At the suite, the processors were stored in large jars to imply that the chips were in production and readily available. The customers did not know the bottom half of each jar contained non-functional chips. The chips were $ 20 and $ 25 while the documentation package was an additional $ 10 . Users were encouraged to make photocopies of

6380-569: The NES was a second source version by Ricoh , a partial system on a chip , that lacked the binary-coded decimal mode but added 22 memory-mapped registers and on-die hardware for sound generation, joypad reading, and sprite list DMA . Called 2A03 in NTSC consoles and 2A07 in PAL consoles (the difference being the clock frequency divider ratio and a lookup table for audio sample rates), this processor

6496-447: The PC and the status flags. This decision halved the interrupt overhead. Another change, and among the most important in terms of practical real-world performance, was the modification of the instruction set to take advantage of page mode DRAM . Recently introduced, page mode allowed subsequent accesses of memory to run twice as fast if they were roughly in the same location, or "page", in

6612-622: The RISC's basic register-heavy and load/store concepts, ARM added a number of the well-received design notes of the 6502. Primary among them was the ability to quickly serve interrupts , which allowed the machines to offer reasonable input/output performance with no added external hardware. To offer interrupts with similar performance as the 6502, the ARM design limited its physical address space to 64 MB of total addressable space, requiring 26 bits of address. As instructions were 4 bytes (32 bits) long, and required to be aligned on 4-byte boundaries,

6728-637: The XEGS. In the 1980s, a popular electronics magazine Elektor/Elektuur used the processor in its microprocessor development board Junior Computer . The CMOS successor to the 6502, the WDC 65C02 , also saw use in home computers and video game consoles. Apple used it in the Apple II line starting with the Apple IIc and later variants of the Apple IIe and also offered a kit to upgrade older IIe systems with

6844-676: The addition of simultaneous multithreading (SMT) for improved performance or fault tolerance . Acorn Computers ' first widely successful design was the BBC Micro , introduced in December 1981. This was a relatively conventional machine based on the MOS Technology 6502 CPU but ran at roughly double the performance of competing designs like the Apple II due to its use of faster dynamic random-access memory (DRAM). Typical DRAM of

6960-660: The architecture, ARMv7, defines three architecture "profiles": Although the architecture profiles were first defined for ARMv7, ARM subsequently defined the ARMv6-M architecture (used by the Cortex M0 / M0+ / M1 ) as a subset of the ARMv7-M profile with fewer instructions. Except in the M-profile, the 32-bit ARM architecture specifies several CPU modes, depending on the implemented architecture features. At any moment in time,

7076-834: The attendees at the WESCON trade show in San Francisco beginning on September 16, 1975. Peddle was a very effective spokesman and the MOS Technology microprocessors were extensively covered in the trade press. One of the earliest was a full-page story on the MCS6501 and MCS6502 microprocessors in the July 24, 1975 issue of Electronics magazine. Stories also ran in EE Times (August 24, 1975), EDN (September 20, 1975), Electronic News (November 3, 1975), Byte (November 1975) and Microcomputer Digest (November 1975). Advertisements for

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7192-459: The chips and documentation, whereas other semiconductor companies only wanted to deal with "serious" customers. For example, Signetics was introducing the 2650 microprocessor and its advertisements asked readers to write for information on their company letterhead. The 6501/6502 introduction in print and at Wescon was an enormous success. The downside was that the extensive press coverage got Motorola's attention. In October 1975, Motorola reduced

7308-467: The circuits, which almost always required a separate external chip that could supply a powerful signal. With the reduced power requirements of depletion-load design, the clock could be moved onto the chip, simplifying the overall computer design. These changes greatly reduced complexity and the cost of implementing a complete system. A wider change taking place in the industry was the introduction of projection masking . Previously, chips were patterned onto

7424-666: The company found the KIM-1 also sold well to hobbyists and tinkerers. The related Rockwell AIM-65 control, training, and development system also did well. The software in the AIM 65 was based on that in the MDT. Another roughly similar product was the Synertek SYM-1 . One of the first "public" uses for the design was the Apple I microcomputer , introduced in 1976. The 6502 was next used in

7540-498: The contemporary 1987 IBM PS/2 Model 50 , which initially utilised an Intel 80286 , offering 1.8 MIPS @ 10 MHz, and later in 1987, the 2 MIPS of the PS/2 70, with its Intel 386 DX @ 16 MHz. A successor, ARM3, was produced with a 4 KB cache, which further improved performance. The address bus was extended to 32 bits in the ARM6, but program code still had to lie within the first 64 MB of memory in 26-bit compatibility mode, due to

7656-599: The cost of competing designs from larger companies, such as the 6800 or Intel 8080 . Its introduction caused rapid decreases in pricing across the entire processor market. Along with the Zilog Z80 , it sparked a series of projects that resulted in the home computer revolution of the early 1980s. Home video game consoles and home computers of the 1970s through the early 1990s, such as the Atari 2600 , Atari 8-bit computers , Apple II , Nintendo Entertainment System , Commodore 64 , Atari Lynx , BBC Micro and others, use

7772-489: The design goal. They also considered the new 32-bit designs, but these cost even more and had the same issues with support chips. According to Sophie Wilson , all the processors tested at that time performed about the same, with about a 4 Mbit/s bandwidth. Two key events led Acorn down the path to ARM. One was the publication of a series of reports from the University of California, Berkeley , which suggested that

7888-418: The details of their proposed 8-bit microprocessor system with ROM, RAM, parallel and serial interfaces. In early 1974, they provided engineering samples of the chips so that customers could prototype their designs. Motorola's "total product family" strategy did not focus on the price of the microprocessor, but on reducing the customer's total design cost. They offered development software on a timeshare computer,

8004-687: The documents, an inexpensive way for MOS Technology to distribute product information. The preliminary data sheets listed just 55 instructions excluding the Rotate Right (ROR) instruction which was not supported on these early chips. The reviews in Byte and EDN noted the lack of the ROR instruction. The next revision of the layout fixed this problem and the May 1976 datasheet listed 56 instructions. Peddle wanted every interested engineer and hobbyist to have access to

8120-484: The earlier 8-bit designs simply could not compete. Even newer 32-bit designs were also coming to market, such as the Motorola 68000 and National Semiconductor NS32016 . Acorn began considering how to compete in this market and produced a new paper design named the Acorn Business Computer . They set themselves the goal of producing a machine with ten times the performance of the BBC Micro, but at

8236-450: The era ran at about 2 MHz; Acorn arranged a deal with Hitachi for a supply of faster 4 MHz parts. Machines of the era generally shared memory between the processor and the framebuffer , which allowed the processor to quickly update the contents of the screen without having to perform separate input/output (I/O). As the timing of the video display is exacting, the video hardware had to have priority access to that memory. Due to

8352-435: The era, the dynamic NMOS 6502 chip is not sequenced by microcode but decoded directly using a dedicated PLA . The decoder occupied about 15% of the chip area. This compares to later microcode-based designs like the Motorola 68000 , where the microcode ROM and decoder engine represented about a third of the gates in the system. Like its precursor, the 6800, the 6502 has very few registers . They include This compares to

8468-635: The first 6800 chips were fabricated in February 1974 and the full family was officially released in November 1974. John Buchanan was the designer of the 6800 chip and Rod Orgill, who later did the 6501, assisted Buchanan with circuit analyses and chip layout. Bill Mensch joined Motorola in June 1971 after graduating from the University of Arizona (at age 26). His first assignment was helping define

8584-512: The high cost of the microprocessor chips. At the same time, these visits invariably resulted in the engineers he presented to producing lists of required instructions that were much smaller than "all these fancy instructions" that had been included in the 6800. Peddle and other team members started outlining the design of an improved feature, reduced size microprocessor. At that time, Motorola's new semiconductor fabrication facility in Austin, Texas ,

8700-531: The index and stack registers effectively with several addressing modes , including a fast "direct page" or "zero page" mode, similar to that found on the PDP-8 , that accesses memory locations from addresses 0 to 255 with a single 8-bit address (saving the cycle normally required to fetch the high-order byte of the address)—code for the 6502 uses the zero page much as code for other processors would use registers. On some 6502-based microcomputers with an operating system,

8816-429: The index register to walk the array byte-wise takes only two additional cycles. With the less frequently used "(indirect,x)" mode the effective address for the operation is found at the zero page address formed by adding the second byte of the instruction to the contents of the X register. Using the indexed modes, the zero page effectively acts as a set of up to 128 additional (though very slow) address registers. The 6502

8932-412: The instruction set. It also designs and licenses cores that implement these ISAs. Due to their low costs, low power consumption, and low heat generation, ARM processors are useful for light, portable, battery-powered devices, including smartphones , laptops , and tablet computers , as well as embedded systems . However, ARM processors are also used for desktops and servers , including Fugaku ,

9048-582: The interrupt itself. This meant FIQ requests did not have to save out their registers, further speeding interrupts. The first use of the ARM2 was the Acorn Archimedes personal computer models A305, A310, and A440 launched in 1987. According to the Dhrystone benchmark, the ARM2 was roughly seven times the performance of a typical 7 MHz 68000-based system like the Amiga or Macintosh SE . It

9164-430: The layout. MOS Technology's microprocessor introduction was different from the traditional months-long product launch. The first run of a new integrated circuit is normally used for internal testing and shared with select customers as "engineering samples". These chips often have a minor design defect or two that will be corrected before production begins. Chuck Peddle's goal was to sell the first run 6501 and 6502 chips to

9280-421: The lower 2 bits of an instruction address were always zero. This meant the program counter (PC) only needed to be 24 bits, allowing it to be stored along with the eight bit processor flags in a single 32-bit register. That meant that upon receiving an interrupt, the entire machine state could be saved in a single operation, whereas had the PC been a full 32-bit value, it would require separate operations to store

9396-493: The market. 1981 was also the year that the IBM Personal Computer was introduced. Using the recently introduced Intel 8088 , a 16-bit CPU compared to the 6502's 8-bit design, it offered higher overall performance. Its introduction changed the desktop computer market radically: what had been largely a hobby and gaming market emerging over the prior five years began to change to a must-have business tool where

9512-410: The new depletion-load design, a single +5 V supply was all that was needed, eliminating all of this complexity. A further advantage was that depletion-load designs used less power while switching, thus running cooler and allowing higher operating speeds. Another practical offshoot is that the clock signal for earlier CPUs had to be strong enough to survive all the dissipation as it traveled through

9628-476: The new design, the cost goal demanded a size goal of 153 by 168 mils (3.9 mm × 4.3 mm), or an area of 16.6 mm . Several new techniques would be needed to hit this goal. Two significant advances arrived in the market just as the 6502 was being designed that provided to be significant cost reductions. The first was the move to depletion-load NMOS . The 6800 used an early NMOS process, enhancement mode, that required three supply voltages. One of

9744-600: The new processor. The Hudson Soft HuC6280 chip used in the TurboGrafx-16 was based on a 65C02 core. The Atari Lynx used a custom chip named "Mikey" designed by Epyx which included a VLSI VL65NC02 licensed cell. The G65SC12 by GTE Microcircuits (renamed California Micro Devices) variant was used in the BBC Master . Some models of the BBC Master also included an additional G65SC102 co-processor. The 6502

9860-459: The now independent MOS Technology was running out of money and had to settle the case. They agreed to drop the 6501 processor, pay Motorola $ 200 ,000 and return the documents that Motorola contended were confidential. Both companies agreed to cross-license microprocessor patents. That May, Motorola dropped the price of a single 6800 microprocessor to $ 35 . By November, Commodore had acquired MOS Technology. With legal troubles behind them, MOS

9976-467: The number of operands that instruction uses. For comparison, the Zilog Z80 required two cycles to fetch memory, and the minimum instruction time was four cycles. Thus, despite the lower clock speeds compared to competing designs, typically in the neighborhood of 1 to 2  MHz , the 6502's performance was competitive with CPUs using significantly faster clocks. This is partly due to a simple state machine implemented by combinational (clockless) logic to

10092-498: The number of register saves and restores performed in procedure calls ; the ARM design did not adopt this. Wilson developed the instruction set, writing a simulation of the processor in BBC ;BASIC that ran on a BBC Micro with a second 6502 processor . This convinced Acorn engineers they were on the right track. Wilson approached Acorn's CEO, Hermann Hauser , and requested more resources. Hauser gave his approval and assembled

10208-456: The order of 100,000 uses rather than 10. This eliminated step-to-step failures and the high flaw rates formerly seen on complex designs. Yields on CPUs immediately jumped from 10% to 60 or 70%. This meant the price of the CPU declined roughly the same amount and the microprocessor suddenly became a commodity device. MOS Technology's existing fabrication lines were based on the older PMOS technology, they had not yet begun to work with NMOS when

10324-494: The original documentation. The next iteration of the design shrank the chip and added the rotate right capability, and ROR was included in revised documentation. MOS would introduce two microprocessors based on the same underlying design: the 6501 would plug into the same socket as the Motorola 6800, while the 6502 re-arranged the pinout to support an on-chip clock oscillator. Both would work with other support chips designed for

10440-549: The peripheral ICs for the 6800 family and later he was the principal designer of the 6820 Peripheral Interface Adapter (PIA). Bennett hired Chuck Peddle in 1973 to do architectural support work on the 6800 family products already in progress. He contributed in many areas, including the design of the 6850 ACIA (serial interface). Motorola's target customers were established electronics companies such as Hewlett-Packard , Tektronix , TRW , and Chrysler . In May 1972, Motorola's engineers began visiting select customers and sharing

10556-587: The price of a single 6800 microprocessor from $ 175 to $ 69 . The $ 300 system design kit was reduced to $ 150 and it now came with a printed circuit board. On November 3, 1975, Motorola sought an injunction in Federal Court to stop MOS Technology from making and selling microprocessor products. They also filed a lawsuit claiming patent infringement and misappropriation of trade secrets. Motorola claimed that seven former employees joined MOS Technology to create that company's microprocessor products. Motorola

10672-512: The reserved bits for the status flags. In the late 1980s, Apple Computer and VLSI Technology started working with Acorn on newer versions of the ARM core. In 1990, Acorn spun off the design team into a new company named Advanced RISC Machines Ltd., which became ARM Ltd. when its parent company, Arm Holdings plc, floated on the London Stock Exchange and Nasdaq in 1998. The new Apple–ARM work would eventually evolve into

10788-494: The right leaders in the Semiconductor Products division." The division was reorganized and the management replaced. The new group vice-president John Welty said, "The semiconductor sales organization lost its sensitivity to customer needs and couldn't make speedy decisions." Peddle began looking outside Motorola for a source of funding for this new project. He initially approached Mostek CEO L. J. Sevin , but

10904-501: The same price. This would outperform and underprice the PC. At the same time, the recent introduction of the Apple Lisa brought the graphical user interface (GUI) concept to a wider audience and suggested the future belonged to machines with a GUI. The Lisa, however, cost $ 9,995, as it was packed with support chips, large amounts of memory, and a hard disk drive , all very expensive then. The engineers then began studying all of

11020-432: The seventeen chip designers and layout people on the 6800 team, eight left. The goal of the team was to design and produce a low-cost microprocessor for embedded applications and to target as wide as possible a customer base. This would be possible only if the microprocessor was low cost, and the team set the price goal for volume purchases at $ 5 . Mensch later stated the goal was not the processor price itself, but to create

11136-484: The simpler design, compared with processors like the Intel 80286 and Motorola 68020 , some additional design features were used: ARM includes integer arithmetic operations for add, subtract, and multiply; some versions of the architecture also support divide operations. MOS Technology 6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") is an 8-bit microprocessor that

11252-502: The simulations on the ARM1 boards led to the late 1986 introduction of the ARM2 design running at 8 MHz, and the early 1987 speed-bumped version at 10 to 12 MHz. A significant change in the underlying architecture was the addition of a Booth multiplier , whereas formerly multiplication had to be carried out in software. Further, a new Fast Interrupt reQuest mode, FIQ for short, allowed registers 8 through 14 to be replaced as part of

11368-403: The surface of the wafer by placing a mask on the surface of the wafer and then shining a bright light on it. The masks often picked up tiny bits of dirt or photoresist as they were lifted off the chip, causing flaws in those locations on any subsequent masking. With complex designs like CPUs, 5 or 6 such masking steps would be used, and the chance that at least one of these steps would introduce

11484-482: The surface. Any chip printed in that location will fail and has to be discarded. Smaller chips mean any single copy is less likely to be printed on a defect. For both of these reasons, the cost of the final product is strongly dependent on the size of the chip design. The original 6800 chips were intended to be 180 by 180 mils (4.6 mm × 4.6 mm), but layout was completed at 212 by 212 mils (5.4 mm × 5.4 mm), or an area of 29.0 mm . For

11600-536: The synthesizable RTL, the customer has the ability to perform architectural level optimisations and extensions. This allows the designer to achieve exotic design goals not otherwise possible with an unmodified netlist ( high clock speed , very low power consumption, instruction set extensions, etc.). While Arm Holdings does not grant the licensee the right to resell the ARM architecture itself, licensees may freely sell manufactured products such as chip devices, evaluation boards and complete systems. Merchant foundries can be

11716-411: The system. Peddle responded to the order by informing Motorola that the letter represented an official declaration of "project abandonment", and as such, the intellectual property he had developed to that point was now his. In a November 1975 interview, Motorola's Chairman, Robert Galvin, ultimately agreed that Peddle's concept was a good one and that the division missed an opportunity, "We did not choose

11832-457: The team arrived. Paivinen promised to have an NMOS line up and running in time to begin the production of the new CPU. He delivered on the promise, the new line was ready by June 1975. Chuck Peddle, Rod Orgill, and Wil Mathys designed the initial architecture of the new processors. A September 1975 article in EDN magazine gives this summary of the design: The MOS Technology 650X family represents

11948-503: The two needed to address the full 64 KB of memory. This provides fast access to the first 256 bytes of RAM by using shorter instructions. For instance, an instruction to add a value from memory to the value in the accumulator would normally be three bytes, one for the instruction and two for the 16-bit address. Using the zero page reduces this to an 8-bit address, reducing the total instruction length to two bytes, and thus improving instruction performance. The stack address space

12064-449: The world's fastest supercomputer from 2020 to 2022. With over 230 billion ARM chips produced, since at least 2003, and with its dominance increasing every year , ARM is the most widely used family of instruction set architectures. There have been several generations of the ARM design. The original ARM1 used a 32-bit internal structure but had a 26-bit address space that limited it to 64 MB of main memory . This limitation

12180-467: Was a billion-dollar company with a plausible case and expensive lawyers. On October 30, 1974, Motorola had filed numerous patent applications on the microprocessor family and was granted twenty-five patents. The first was in June 1976 and the second was to Bill Mensch on July 6, 1976, for the 6820 PIA chip layout. These patents covered the 6800 bus and how the peripheral chips interfaced with the microprocessor. Motorola began making transistors in 1950 and had

12296-511: Was as a second processor for the BBC Micro, where it helped in developing simulation software to finish development of the support chips (VIDC, IOC, MEMC), and sped up the CAD software used in ARM2 development. Wilson subsequently rewrote BBC BASIC in ARM assembly language . The in-depth knowledge gained from designing the instruction set enabled the code to be very dense, making ARM BBC BASIC an extremely good test for any ARM emulator. The result of

12412-594: Was declined. Sevin later admitted this was because he was afraid Motorola would sue them. While Peddle was visiting Ford Motor Company on one of his sales trips, Bob Johnson, later head of Ford's engine automation division, mentioned that their former colleague John Paivinen had moved to General Instrument and taught himself semiconductor design. Paivinen then formed MOS Technology in Valley Forge, Pennsylvania in 1969 with two other executives from General Instrument, Mort Jaffe and Don McLaughlin. Allen-Bradley ,

12528-406: Was designed by a small team led by Chuck Peddle for MOS Technology . The design team had formerly worked at Motorola on the Motorola 6800 project; the 6502 is essentially a simplified, less expensive and faster version of that design. When it was introduced in 1975, the 6502 was the least expensive microprocessor on the market by a considerable margin. It initially sold for less than one-sixth

12644-435: Was every other cycle, there was no need to signal the CPU to avoid using the bus, making this sort of access easy to implement without any bus logic. When faster memories became available in the 1980s, newer machines could use this same technique while running at higher clock rates, the BBC Micro used newer RAM that allowed its CPU to run at 2 MHz while still using the same bus sharing techniques. Like most simple CPUs of

12760-532: Was having difficulty producing MOS chips, and mid-1974 was the beginning of a year-long recession in the semiconductor industry. Also, many of the Mesa, Arizona employees were displeased with the upcoming relocation to Austin. Motorola's Semiconductor Products Division management showed no interest in Peddle's low-cost microprocessor proposal. Eventually Peddle was given an official letter telling him to stop working on

12876-458: Was often found on workstations. The graphics system was also simplified based on the same set of underlying assumptions about memory and timing. The result was a dramatically simplified design, offering performance on par with expensive workstations but at a price point similar to contemporary desktops. The ARM2 featured a 32-bit data bus , 26-bit address space and 27 32-bit registers , of which 16 are accessible at any one time (including

12992-580: Was produced exclusively for Nintendo . 6502 or variants were used in all of Commodore's floppy disk drives for all of their 8-bit computers, from the PET line through the Commodore 128D, including the Commodore 64. 8-inch PET drives had two 6502 processors. Atari used the same 6507 used in the Atari VCS for its 810 and 1050 disk drives used for all of their 8-bit computer line, from the 400/800 through

13108-679: Was removed in the ARMv3 series, which has a 32-bit address space, and several additional generations up to ARMv7 remained 32-bit. Released in 2011, the ARMv8-A architecture added support for a 64-bit address space and 64-bit arithmetic with its new 32-bit fixed-length instruction set. Arm Holdings has also released a series of additional instruction sets for different rules; the "Thumb" extension adds both 32- and 16-bit instructions for improved code density , while Jazelle added instructions for directly handling Java bytecode . More recent changes include

13224-543: Was still left with the problem of getting developers to try their processor, prompting Chuck Peddle to design the MDT-650 ("microcomputer development terminal") single-board computer . Another group inside the company designed the KIM-1 , which was sold semi-complete and could be turned into a usable system with the addition of a 3rd party computer terminal and compact cassette drive. While it sold well to its intended market,

13340-572: Was the most widely used architecture in mobile devices as of 2011 . Since 1995, various versions of the ARM Architecture Reference Manual (see § External links ) have been the primary source of documentation on the ARM processor architecture and instruction set, distinguishing interfaces that all ARM processors are required to support (such as instruction semantics) from implementation details that may vary. The architecture has evolved over time, and version seven of

13456-493: Was twice as fast as an Intel 80386 running at 16 MHz, and about the same speed as a multi-processor VAX-11/784 superminicomputer . The only systems that beat it were the Sun SPARC and MIPS R2000 RISC-based workstations . Further, as the CPU was designed for high-speed I/O, it dispensed with many of the support chips seen in these machines; notably, it lacked any dedicated direct memory access (DMA) controller which

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